1. Field of the Invention
The present invention relates to systems configured for providing advanced telephony-type services for subscribers in a voice over Internet Protocol (IP) network according to H.323 protocol.
2. Description of the Related Art
The evolution of the public switched telephone network has resulted in a variety of voice applications and services that can be provided to individual subscribers and business subscribers. Such services include voice messaging systems that enable landline or wireless subscribers to record, playback, and forward voice mail messages. However, the ability to provide enhanced services to subscribers of the public switched telephone network is directly affected by the limitations of the public switched telephone network. In particular, the public switched telephone network operates according to a protocol that is specifically designed for the transport of voice signals; hence any modifications necessary to provide enhanced services can only be done by switch vendors that have sufficient know-how of the existing public switched telephone network infrastructure. Hence, the reliance on proprietary protocols and closed development environments by telecommunications equipment providers has limited service providers to vendor-specific implementations of voice and telephony services.
Of particular concern is the limited scalability of user interface applications configured for providing prescribed services to subscribers based on deployed telephony applications. In particular, user interface applications typically are deployed within a single telephony component of the telecommunications network, limiting the ability of the user interface applications to be distributed across multiple components within the telecommunications network.
One example of limited scalability in a user interface application involves conventional voice mail applications that limit a voice mail subscriber to merely retrieve stored voice mail messages, and possibly forward a voice mail message to another voice mail subscriber within the same voice mail system. However, these conventional voice mail applications do not permit a voice mail subscriber to perform more advanced operations. Moreover, these conventional voice mail applications are typically deployed on a single telephony component, limiting the scalability of the conventional voice mail application as the number of subscribers are increased.
U.S. Pat. No. 5,857,013 to Yue et al. suggests the desirability of enabling a mobile telephone user to access his or her associated voice mail system and have the system automatically call a number of a person, having left a message, without leaving the voice mail service. Yue et al. merely suggests use of a Bell South service circuit node, available from AT&T network systems, where the system software is coded in the service logic language within a UNIX environment. Yue et al., however, provides no disclosure of how such a system would be implemented outside the service circuit node, for example in a telephone network such as a mobile telephone system or the public switched telephone network. Hence, Yue et al. suffers from the same disadvantages described above that deployment on a single telephony component limits the scalability of the voice application to be deployed.
Another example of limited scalability in a user interface application involves voice activated dialing applications, where the subscriber relies on speech recognition resources within an interactive voice response unit to initiate an outgoing call in response to a spoken command. For example, a subscriber accessing the interactive voice response unit may utter the phrase “call mom” to initiate a call to a number preprogrammed by the subscriber; the interactive voice response unit, in response to receiving the phrase “call mom”, interprets the phrase and accesses the preprogrammed number in order to initiate an outgoing call for the subscriber. As described above, however, such applications are severely limited to a telephony component (such as an integrated voice response unit integrated with a telephony switch) having specialized resources programmed by switch vendors, hence lack scalability for wide scale deployment.
Voice over IP technology is under development as part of an alternative open packet telephony communications network, distinct from the public (circuit switched) telephone network, capable of using packet switched networks for integrating voice, data, facsimile, and Internet services, and the like. New packet telephony voice services are being built from open standards such as The International Telecommunications Union (ITU) Recommendation H.323. Recommendation H.323 defines the components, procedures, and protocols necessary to provide audiovisual communications on local area networks. Recommendation H.323 is based on the Real Time Protocol/Control Protocol (RTP/RTCP) of the Internet Engineering Task Force (IETF), and applies to either point-to-point or multipoint sessions, and references many other ITU recommendations, including H.225 and H.245. Recommendation H.225 specifies messages for call control including signaling, registration and admissions, and packetization/synchronization of media streams. Recommendation H.245 specifies messages for opening and closing channels for media streams, and other commands, requests and indications. However, the current H.323 standard does not provide a direct means for enabling a voice mail subscriber to place an outbound call from a voice mail system, and then return to the voice mailbox after call completion.
Hence, the existing voice over IP technology has yet to produce a scalable technology for deployment of advanced voice application services across multiple platforms of an IP-based telecommunications system.